Association of high Plasmodium falciparum parasite densities with polyclonal microscopic infections in asymptomatic children from Toubacouta, Senegal

Malaria Journal

Ibrahima Dia¹  Cheikh Loucoubar²  Joseph Faye²  Mbacké Sembène³  Babacar Diouf⁴  Aïssatou Toure-Balde⁴  Makhtar Niang⁴  Ronald Perraut⁴  Fode Diop⁴  Yakhya Dieye⁵ 

[1] Entomology Unit, Institut Pasteur Dakar;Epidemiology of Infectious Diseases Unit, Institut Pasteur Dakar;Faculté des Sciences et Techniques, Université Cheikh Anta Diop;Immunology Unit, Institut Pasteur Dakar;Virology Unit, Institut Pasteur Dakar;

关键词: Plasmodium falciparum;    Polymorphism;    msp-1;    msp-2;    Asymptomatic;   

DOI  :  10.1186/s12936-019-2684-3

来源: DOAJ

【 摘 要 】

Abstract Background Malaria is a leading cause of mortality and morbidity in tropical countries, especially in sub-Saharan Africa. In Senegal, a control plan implemented in the beginning of the 2000s has enabled a substantial reduction of mortality and morbidity due to malaria. However, eradication of malaria requires a vaccine that protects against Plasmodium falciparum the deadliest species of the parasite that causes this disease. Plasmodium falciparum is characterized by an extensive genetic diversity that makes vaccine development challenging. In this study, the diversity of P. falciparum isolates was analysed from asymptomatic children residing in the district of Toubacouta, Senegal. Methods A nested PCR approach was used to perform genotyping of the msp-1 and msp-2 loci in samples from 87 asymptomatic children infected with P. falciparum, collected during a cross sectional survey in November and December 2010. Parasite densities in blood samples were determined by microscopic examination and statistical analyses were used to identify association of parasite genotype and parasitaemia. Results Genotyping was successful in 84/87 and 82/87 samples for msp-1 and msp-2, respectively. A strong genetic diversity was found with a total of 15 and 21 different alleles identified for msp-1 and msp-2, respectively. RO33 was the most frequent allelic family of msp-1 followed by MAD20, then by K1. Regarding msp-2 allelic families, 3D7 was more common than FC27. Multiple infections were predominant, since 69% and 89% of the samples genotyped for msp-1 and msp-2 showed more than one clone of P. falciparum with complexity of infection (COI) of 2.5 and 4.7, respectively. Expected heterozygosity (HE) was 0.57 and 0.55 for msp-1 and msp-2, respectively. Interestingly, polyclonal infections were significantly associated with higher parasitaemia. Conclusions The strong genetic diversity of P. falciparum clones and the association of polyclonal infection with high parasitaemia call for a multi-allelic approach in the design of vaccine candidates for efficient malaria eradication.

【 授权许可】

Unknown